Atoms, Molecules and Chemical Bonds

Flashcards based on lecture notes about atoms, molecules, chemical bonds, and water properties.

Element

A substance that cannot be broken down by chemical reactions.

Trace elements

Elements required in minute amounts, but their lack can cause severe disorders.

Atom

The smallest unit of matter that retains the properties of an element.

Proton

Positively charged subatomic particle located in the atomic nucleus.

Neutron

Neutral subatomic particle located in the atomic nucleus.

Electron

Negatively charged subatomic particle orbiting the atomic nucleus.

Atomic number

The number of protons in the nucleus of an atom.

Mass number

The total number of protons and neutrons in the nucleus of an atom.

Isotopes

Atomic forms of the same element with different numbers of neutrons.

Molecule

Atoms held together by covalent or ionic bonds.

Polar covalent bond

Unequal sharing of electrons between atoms.

Non-polar covalent bond

Equal sharing of electrons between atoms.

Ionic bond

Attraction between oppositely charged ions.

Hydrogen bond

Weak attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Van der Waals forces

Weak, short-range attraction between atoms due to transient fluctuations in electron distribution.

Cohesion

Tendency of water molecules to stick together due to hydrogen bonding.

Specific heat

The amount of heat that must be absorbed or lost for 1g of a substance to change its temperature by 1°C.

Solvent

A liquid that is a homogeneous mixture of two or more substances.

Hydrophilic

Substances that dissolve in water.

Hydrophobic

Substances that do not dissolve in water.

Molarity

The number of moles of solute per liter of solution.

Acid

A substance that increases the hydrogen ion (H+) concentration of a solution.

Base

A substance that reduces the hydrogen ion (H+) concentration of a solution.

pH

A measure of the hydrogen ion (H+) concentration in a solution.

Buffer

A substance that minimizes changes in pH by absorbing or releasing hydrogen ions.